Hair straightening or hair relaxing products have been commercially available for over fifty years for people who want straighter, more manageable hair. Most commercially available hair relaxers are composed of a strong hydroxide base that breaks the bonds in the hair.
Commercial products based only on alkaline metal hydroxides such as sodium hydroxide and lithium hydroxide are typically used to straighten or relax curly/kinky hair. There are primarily four different types of alkaline metal hydroxide hair straighteners in use: calcium hydroxide, lithium hydroxide, sodium hydroxide, and potassium hydroxide. The straightening product is usually applied quickly and can only remain in the hair for a very limited amount of time. Due to the alkalinity of such products, if the product is not rinsed from the hair at the appropriate time, damage to the hair can occur, as well as chemical burns to the scalp and areas surrounding the hair.
Other relaxing formulations use guanidinium hydroxide which can be formed from the reaction of guanidine carbonate and a very small amount of soluble hydroxide such as calcium hydroxide. The reaction between these two compounds leads to the formation of guanidinium hydroxide and calcium carbonate, which precipitates in the composition. The presence of this precipitate makes the final rinsing of the hair much more difficult and leaves on the hair and the scalp mineral particles that give it a coarse feel and an unattractive appearance resembling dandruff, although such a system may provide a better relaxing efficacy and better skin tolerance. However, these technologies using hydroxide bases are very aggressive for the hair and the scalp and require very strict control of the application time to avoid excessive irritation and impairment of the hair, which may go as far as breaking of the hair.
Other hair relaxing or straightening systems may involve the use of protein denaturants in combination with heat in the absence of hydroxide or non-hydroxide bases. Protein denaturants are compounds which cause a reversible unfolding of a protein.
Thus, the object of the present invention is to provide a hair straightening or relaxing process which is safer than, yet more effective as, conventional processes. It was surprisingly discovered that the use of such a process involving the use of at least one non-hydroxide base, at least one protein denaturant, and a combination of heat and means for physically smoothing hair resulted in significantly better straightening efficiency.